The disclosure relates to tool dies used for forming green ceramic bodies. More particularly, the disclosure relates to tool dies having a wear resistant coating. Even more particularly, the disclosure relates to tool dies having a wear resistant coating having multiple layers.
Ceramic products, such as honeycomb structures that are used as filters and catalyst supports, are typically manufactured by extrusion through at least one extrusion die to form green bodies that are then dried and fired to produce strong, refractory ceramic structures. Such dies are presently made from durable metals or alloys such as tool steels or stainless steels. Dies are subject to rapid wear from the ceramic batch materials that are extruded, and must be discarded when the amount of wear prevents extrusion of products that meet specifications.
A wear resistant coating is often applied to such dies to extend their service life. Such coatings are sometimes fabricated from refractory materials such as inorganic carbides, nitrides, and combinations thereof using chemical vapor deposition. Due to their hardness and surface roughness, however, such coatings require a long period of pre-conditioning or break-in before they are suitable for use in production. Such pre-conditioning is sometimes so long as to consume a significant portion of the useful life of the die.